A pulsed semiconductor laser side-pumped Nd:YAG synchronous acousto-optic modulated Q-switched nanosecond laser are reported. Using a Nd:YAG side-pumped module with a continuous output power of 50 W, a stable Q-switched pulse output with an average output power of 2.27 W and a pulse width of 71 ns is achieved when the semiconductor laser is pumped with a pulse width of 250 μm, a repetition frequency of 1 kHz, and an acousto-optical Q-switching delay of 270 μm.